Neo-Babylonian (NB) was the last surviving dialect of the Semitic language known as Akkadian and it was still being used for the compilation of records at the beginning of our era. Many thousands of NB economic and legal documents and letters exist, particularly from the sixth century B.C., yet the language is still to be studied, as the various ways in which a word could be spelled suggested it was no longer coherent as a language and therefore that it was not worth studying. Aramaic was presumed to have taken over. I have attempted to find out if this is the case by making a synchronic grammatical study of the NB dialects of Babylon and Uruk from 556 to 500 B.C. These cities have been chosen because they have produced considerable amounts of material. The period also spans the Persian conquest of 539 B.C. Part one deals with syntax and morphology. Consistency of syntactical patterns indicates that NB was a living and evolving language and that the influence of Aramaic and Old Persian was minimal. Part two deals with orthography and suggestions on pronunciation and stress. The main difficulty in establishing how much NB has changed from earlier phases of Akkadian (including earlier NB) lies in understanding how the loss of short final vowels has changed word shape. The extent to which words could end in consonant clusters is not clear as cuneiform is unable to represent consonant clusters in word final position. I conclude that the lack of difference between the NB dialects of Babylon and Uruk suggests that efforts were being made to preserve the language and that the scribal teaching methods must have been similar in the two cities.